This invention relates to a hydraulic control valve assembly. In particular, this invention relates to a pre-cored valve body adaptable to provide a first valve assembly having two independent circuits, or a second valve assembly having a single circuit with an interrupted series function.
Conventionally, valve assemblies of the type employed in fluid systems for controlling fluid flow to a plurality of fluid motors comprise a plurality of independent valve units, typically connected in series, for directing fluid flow from a fluid supply source to operate the fluid motors associated with the respective valve units. Such fluid systems frequently have diverse valve function requirements, commonly employing, for example, valve assemblies which provide a plurality of independent circuits within a single valve housing, or which provide a single circuit having multiple interrupted series functions within a single valve housing, according to the requirements of a specific fluid system.
Fluid systems employing valve assemblies of both types are commonly associated with a variety of equipment, including earthworking equipment such as hydraulic excavators and motor graders. Examplary of fluid systems employing both types of valve assemblies is the three-pump hydraulic circuit for a hydraulic excavator described in U.S. Pat. Ser. No. 207,027, by Bridwell, et al filed Dec. 13, 1971, and of common assignment herewith.
At present, valve assemblies are conventionally manufactured as independent units having the desired valve function within each separate unit. Such manufacturing techniques require diversified casting and tooling efforts and involve relatively complicated production and distribution techniques.
Attempts have been made to diversify such specialized valve assemblies for more universal use. For example, the multiple spool valve assembly described in U.S. Pat. No. 3,195,571 and British Pat. No. 835,331 is provided with a carryover fitting effective, inter alia, to establish fluid communication between this and another valve assembly for example, for series operation of a plurality of fluid motors. Also, U.S. Pat. No. 2,868,227 describes a valve housing cored to permit selective blocking of the valve circuits for single or multiple use of the valve assembly.
While the assemblies described attempt to facilitiate single or multiple use of specialized valve units, the valve units per se are not adaptable for use according to valve function requirements of various fluid systems, and afford minimal versatility of function for use under varying system requirements.